I am a sceptic too. Although there are many anecdotal reports, as far as I know there is no study that has comfirmed a link - partly because of the difficulty of implementing such a study. Everyone has different stress thresholds, so unless you wired-up participants long-term to a heart-rate monitor, or some such, you couldn’t determine whether they’d been under comparable levels of stress. What is highly stressful to one individual may be water off a duck’s back to another.
I think it’s fairly commonly agreed that stress can exacerbate symptoms, but that is not the same as triggering a relapse.
In my own case, I do know that if there is any link, it’s can’t be a straightforward one, as I’ve gone through periods of great stress, without anything happening at all. I watched my father succumb to a devastating industrial illness - very painful, and completely without hope. We had to have a court case over it, and an inquest, and everything. If anything was guaranteed to provoke a relapse, you’d have thought that would have done it, but nothing happened. So it isn’t simple.
I hope your counselling has helped you, and you’re not now regretting it out of fears it might have triggered the relapse. You will never know for sure one way or the other, but I don’t think the link is established. I think occasional relapses are still to be expected, regardless of treatment, and regardless what’s going on in life. It could have been complete coincidence.